The present invention is directed to composite materials formed of a matrix and inclusions within the matrix. The material forming the inclusions has a ductility which is greater than that of the material forming the matrix. Ductility may be considered as the resistance to fracture exhibited by a given material. The provision of such ductile inclusions results in a material having increased fracture toughness. Although the invention is generally concerned with metals, and especially aluminum alloys, the present invention also is applicable to other materials, such as ceramics.
Certain materials exhibit properties of great interest, such as high strength, corrosion resistance, etc., but suffer from brittleness. Examples of such materials include high strength ceramics for engine components and certain high strength aluminum alloys. The fracture toughness of such materials can be improved by utilizing these materials as a matrix and providing a dispersion of ductile islands (inclusions) within the matrix. It is therefore an object of this invention to provide composite materials which have the desired properties of the base material as well as improved fracture toughness.